The present invention relates to a light illuminating type switch utilized in a portable information apparatus.
A prior light illuminating type switch, for example, Japanese Patent Application No. 67095/1999 previously proposed by the applicant, as shown by FIG. 5 and FIG. 6, is a structure where fixed contacts A are on an upper side of a base sheet B. An upper side of a dome shaped movable contact C is attached with a flexible electro-luminescent (EL) sheet E by an adhering agent F while interposing an insulating member D.
According to the prior light illuminating type switch, a characteristic of switch operation feeling in operating to depress and release a switch, called the click characteristic, is inferior to the click characteristic for the case of a single member of a metal dome which is not attached with the insulating member D and the EL sheet E. That is, where a click rate of the single member of a metal dome achieved 49%. The prior structure attached with the EL sheet has a click rate of 43%.
According to the invention, there is provided a light illuminating type switch that has a click rate and a click characteristic near to that of the single member of the metal dome, i.e. 49%.
According to an aspect of the invention, a light illuminating type switch has a base sheet with a fixed contact, wherein an upper side of the base sheet is arranged with a dome shaped movable contact brought into contact with and separated from the fixed contact in moderation by being elastically deformed. A surface of the movable contact is attached with a flexible EL sheet extended along the surface over to a peripheral portion of the movable contact via an insulating member. The EL sheet is partially formed with at least one cut portion at a position along an outer peripheral edge of the dome shaped movable contact. The cut portions promote the click characteristics.
It is preferable that at least one pair of cut portions are formed at symmetrical positions centering on the movable contact. Further, it is preferable that the movable contact and the insulating member are attached to each other by an adhering agent or an adhesive double-coated sheet.